Detection of a subject's point-of-gaze is a technique important for and essential to establishment of modern and next-generation information environments. Techniques relating to point-of-gaze detection have a wide range of applications, such as user interfaces, ubiquitous and ambient environments, human behavior recognition/understanding, communication analysis, etc., which use point-of-gaze information. Accordingly, various techniques have been reduced in practice in addition to implementation to commercially available products.
Non-patent Document 1 discloses a technique using an environment image reflected on the surface of an eyeball as a novel point-of-gaze detecting method. This technique achieves point-of-gaze detection by direct mapping between an environment image reflected on the surface of an eyeball and points of a scene captured by an environment camera. This technique has various advantages, such as: (1) system installation is easy; (2) the need of equipment fitting to a subject is eliminated; (3) a complicate depth-varying environment can be addressed; and the like.